Ketamine-induced mitochondrial dysfunction and nitric oxide alterations in brain cortex synaptosomes.

GUERRA, J.I.; KARADAYIAN, A.,; CARRERE, L.; LORES ARNAIZ, S.

Buenos Aires

Simposio; Frontiers in Bioscience Symposium 4th edition.; 2023

Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA), Partner Institute of the Max Planck Society

Ketamine is an anesthetic agent acting as an uncompetitive antagonist of N-methyl-D-aspartate receptor. At sub-anesthetic doses, ketamine is a potent and fast-acting antidepressant, while at high doses it has been emerging as a drug of abuse. Previous results by our group have shown that ketamine induces impairment of calcium homeostasis and cell apoptotic death in PC-12 cells. The aim of this study was to evaluate the molecular mechanisms involved in ketamine neurotoxicity by evaluating in vitro effects of the drug on mitochondrial function and nitric oxide (NO) production in brain cortex synaptosomes. Brain cortex synaptosomes were isolated from male 3-month-old Swiss mice by Ficoll gradient procedures. Samples were incubated with ketamine in different concentrations (50, 250 and 500 µM) during 5 minutes at 37oC. Mitochondrial membrane potential, superoxide and nitric oxide levels were determined by flow cytometry. In addition, the activity of enzymatic respiratory complexes and acetylcholinesterase were determined by spectrophotometric methods. Synaptosomal samples exposed to 500 µM ketamine showed a 20% decrease in mitochondrial membrane potential. Superoxide levels were decreased by 25% after incubation with 50 µM ketamine, recovering normal values at higher ketamine concentrations.Preliminary data show impairment of respiration parameters and decreased activity of complex I-III and complex IV after treatment with 500 µM ketamine.Synaptosomes exposed to ketamine showed decreased basal levels of NO compared to control samples, being values 16% lower in the case of 500 µM ketamine. After glutamate addition (up to 1 mM) NO production increased in control synaptosomes but remained at lower levels in ketamine-treated samples.Finally, acetylcholinesterase activity decreased 38% and 29% in synaptosomal fractions incubated with 250 and 500 µM ketamine respectively.In summary, in vitro ketamine treatment induces mitochondrial dysfunction and impairment of NO production in brain cortex synaptosomes. Nitric oxide does not seem to be involved in ketamine-induced mitochondrial alterations.